If you’re self-employed and working for an employer that offers a traditional 401(k), you’ve probably wondered — can you contribute the maximum to both plans? The answer is yes, but only if you understand how the IRS rules work.
At My Solo 401k Financial, we help self-employed professionals legally maximize their retirement savings while staying compliant. Let’s break down how you can make the most of both your employer 401(k) and your Solo 401(k).
Watch: Complete breakdown of how you can contribute to both plans
1. Solo 401(k) Eligibility
Before contributing, make sure you qualify to open a Solo 401(k):
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You must have self-employment income (from freelancing, consulting, or a side business).
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You cannot have full-time W-2 employees (other than your spouse).
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You may hire part-time workers who work under 1,000 hours per year.
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Your spouse can participate if they work in the same business, even if they’re not an owner.
2. Understanding the Two Buckets: Employee vs. Employer Contributions
When contributing to both your job’s 401(k) and your Solo 401(k), there are two main categories:
Employee Contributions (Shared Across All 401(k)s)
For 2025, the employee deferral limit is:
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$23,500 if under age 50
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$31,000 if age 50+ (includes $7,500 catch-up)
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$34,750 for ages 60–63 (includes $11,250 “super catch-up” under SECURE Act 2.0)
These employee contributions apply across all 401(k) plans combined.
That means you can’t contribute $23,500 to both your employer’s plan and your Solo 401(k) — the limit is shared.
Employer (Profit-Sharing) Contributions (Separate Per Business)
Employer contributions, however, are unique to each business:
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Up to 25% of W-2 wages if your business is an S-Corp.
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Up to 20% of net earnings if you’re a sole proprietor or partnership.
This means you can double up on employer contributions — one from your job and one from your self-employment.
3. Real-World Example
Let’s say Jack works full-time at Oracle and also runs an IT consulting business on the side.
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From his Oracle job:
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Contributes $23,500 to his 401(k)
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Oracle adds a $20,000 employer match
Total = $43,500
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From his consulting business (S-Corp):
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Pays himself $80,000 in W-2 wages
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Can contribute $20,000 (25%) in employer profit sharing
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✅ Total across both plans = $63,500
All 100% legal — because employee deferrals are shared, but employer contributions are not.
4. Avoid Excess Contributions
Be careful not to:
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Double-count your employee deferrals across plans.
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Forget that employer contributions are separate.
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Go over IRS limits — excess contributions can trigger penalties and require correction filings.
Each Solo 401(k) has three buckets — pre-tax, Roth, and voluntary after-tax. Keeping separate accounts for each bucket helps track contributions and avoid mistakes.
5. Bonus Strategy: The Mega Backdoor Roth
Here’s where the Solo 401(k) really shines.
With a Solo 401(k) that allows voluntary after-tax contributions (like those offered by MySolo401k.net), you can make additional contributions beyond your regular limits and immediately convert them to Roth — the Mega Backdoor Roth strategy.
Why it’s powerful:
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These after-tax contributions are not impacted by your job’s 401(k).
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You can add up to the overall Solo 401(k) limit ($70,000 for tax year 2025).
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You get tax-free growth once converted to Roth.
Even if you’ve already maxed out your work 401(k), you can still take full advantage of this Solo 401(k) feature.
6. Reporting and Compliance
At My Solo 401k Financial, we handle:
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Form 5500-EZ (if plan assets exceed $250,000)
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Form 1099-R for distributions and Roth conversions
Both are included in your annual plan service — no extra fees.
7. Key Takeaways
✅ You can contribute to both an employer 401(k) and a Solo 401(k).
✅ Employee contributions are shared across all plans.
✅ Employer contributions are separate — and can be made for each business.
✅ Voluntary after-tax contributions are also separate and unlock the Mega Backdoor Roth strategy.
✅ Always track your totals to avoid excess contributions.
